EP2270319B2 - Method and device for cleaning particulate filters in exhaust gas systems of combustion engines - Google Patents

Abstract

The method involves spraying a noncombustible, ash-free cleaning fluid e.g. aqueous alkaline fluid, into a particle filter at high pressure by a spray nozzle (14). Exhaust gas flows across area of the particle filter during an operation of the combustion engine in a quantity such that an interior of the particle filter is completely soaked. The cleaning fluid is injected at pressure of from 6 to 8 bars. The quantity of the cleaning fluid to be injected corresponds approximately to a half volume of the particle filter. An independent claim is also included for an apparatus for the executing a method for cleaning particle filters in an exhaust gas system of a combustion engine of a motor vehicle.

Description

The invention relates to a method for cleaning particulate filters in exhaust systems of internal combustion engines, in particular of diesel engines in vehicles.

In view of the increasing demands on environmental and climatic compatibility nowadays more and more vehicles, which are operated in particular with diesel engines, equipped with particulate filters, which are usually arranged in the exhaust system behind the catalyst to incompletely burned fuel in the form of soot and Rußagglomeraten to filter out of the exhaust. Naturally, such a particle filter increases in the course of operation, because it is clogged more and more by the retained soot particles. Therefore, regeneration of the particulate filter is required from time to time.

The regeneration of the particulate filter is usually carried out in vehicles either in that the engine is operated with increased load, which leads to an increase in the exhaust gas temperature in the particulate filter. This increase in the exhaust gas temperature causes the retained soot particles are subsequently burned in the soot particle filter, whereby the particulate filter is free again. Such passive regeneration takes place in vehicle engines, for example in highway driving at high speed.

However, if a vehicle is mainly moved only on urban roads or over short distances on rural roads, so that there is no passive regeneration of the particulate filter for an extended period, an active regeneration must be carried out, which takes place when a corresponding sensor system, for example in the pressure sensor in front of and behind the particulate filter it is determined that the passage through the filter is too low, so that the filter must be regenerated.

Thus, if the engine control determines that an active regeneration is to be performed, for example, the fuel injection time is retarded, which also leads to an increased exhaust gas temperature in the particulate filter, since the fuel is also burned in the exhaust system in this case. This increase in the exhaust gas temperature leads to a Burning the retained soot particles, so the incompletely burned fuel in the particulate filter.

If, for example, due to the driving conditions, there is still no regeneration, the driver is called to visit the workshop. The workshop can electronically cause the engine control unit to regenerate manually.

However, this method is only possible up to a certain load state. If this "manual" regeneration is no longer possible, the part of the exhaust system of the vehicle which in addition to the particle filter also contains the catalyst is usually replaced in this case today. Here, the operator of the vehicle at most the choice between the purchase of a brand new particulate filter or a factory-cleaned particulate filter along with the corresponding assembly of the exhaust system, but in both cases leads to significant costs for the vehicle operator.

The JP 2004-239072 A describes a method and apparatus for cleaning particulate filters in a disassembled state in which a particulate filter is sprayed from above through nozzles of hot water so that combustion residues such as ashes are washed away.

The DE 101 18 864 A1 concerns a further method and a device for cleaning a soot particle filter of an exhaust gas purification device, in which the exhaust gas purification device first has to be removed from the motor vehicle in order to be able to use it in a corresponding cleaning device. The exhaust gas purification device is placed vertically with the soot filter down. From above, compressed air is supplied from a compressed gas source through the exhaust gas inlet, which exits through a connecting piece. Then, flushing agent is supplied from below through the exhaust outlet arranged at the bottom, which is pumped through the soot filter body counter to its usual flow direction and flows through the nozzle. Once the soot filter has been sufficiently rinsed, the detergent supply is turned off, and after switching the valve, the remaining in the exhaust gas purification device rinsing agent is blown out by means of compressed air from the soot filter and the exhaust gas purification device.

The JP 57-163113 A describes a method for cleaning a filter in the exhaust system of an internal combustion engine in the installed state, in which wash water is sprayed under pressure via a valve through a nozzle on the filter.

The EP 1 181 966 A1 relates to a method and a device for cleaning filters in the installed state, in which washing water is introduced, for example, from the windscreen washer via a nozzle during operation of the engine in an exhaust gas flow in the conduit and transported with this through the filter.

Based on this, the object of the invention is to provide a workshop-compatible method for cleaning particulate filters in exhaust systems of internal combustion engines, in particular of diesel engines, in vehicles, which makes it possible to inexpensively clean a particulate filter in a simple manner, without requiring the expansion of the particulate filter ,

This object is achieved by the method according to claim 1, which can be carried out particularly advantageously using a device according to claim 10. Advantageous embodiments and further developments of the invention are described in the corresponding subclaims.

Thus, for the purpose of cleaning particulate filters in exhaust systems of internal combustion engines, a non-flammable, ashless cleaning fluid is sprayed into the surface of the particulate filter through a jet of exhaust gas flowing through the exhaust gas during operation of the internal combustion engine by means of a spray nozzle in such an amount that the interior of the particulate filter is substantially completely filled gets soaked. In this way, in the particle filter, the particles retained therein, ie in particular soot, can be detached from the walls of the particle filter so that they can then be removed from the particle filter together with the cleaning liquid.

Since the method according to the invention can also be carried out in particular when the particulate filter is located in the exhaust system of the motor vehicle, ie does not need to be removed, this results in a cost-saving, workshop-oriented method which can be carried out without much effort.

Appropriately, the cleaning liquid is injected at a pressure of 5 to 12, in particular from 6 to 8 bar. This ensures that the cleaning liquid can be effectively injected into particulate filters in these, if they are heavily added, so that it comes to a speedy cleaning.

In order to achieve complete wetting of the interior of the particle filter, it is expedient for the amount of cleaning liquid to be injected to correspond to approximately half the volume of the particle filter (25).

In order to further increase the effectiveness of the cleaning of a particulate filter, it is advantageously provided that the cleaning liquid is injected in succession in two, three or more portions, the time interval between the individual injection processes being 1 to 10 minutes, preferably 3 to 7 minutes, in particular 5 minutes. By inventively provided contact time for the cleaning liquid, the cleaning efficiency is significantly improved.

Another embodiment of the invention is characterized in that the cleaning liquid is injected into the 10 ° C to 100 ° C, preferably 40 ° C to 70 ° C warm particulate filter. As a result, effective cleaning results can be achieved even with a relatively short exposure time.

In another advantageous development of the invention, it is provided that, after the injection of the cleaning liquid, an ashless, nonflammable rinsing liquid is injected into the particle filter, wherein the rinsing liquid is injected at the same pressure as the cleaning liquid. By the subsequent rinsing of the particle filter with a rinsing liquid which is injected under high pressure, the cleaning fluid loaded with soot can already be largely removed from the filter in the workshop.

When a rinsing operation is performed, it is desirable that the rinsing liquid be after a waiting time after completion of the injection of the cleaning liquid, which is equal to or longer than the time period between the individual injections for cleaning liquid to come to the cleaning liquid to its full effect to let.

Suitable cleaning fluids are, in particular, aqueous, alkaline liquids which are not flammable and which can be removed without residue from the particle filter or can evaporate therefrom.

For a particularly simple implementation of the method according to the invention is a device with a to be cleaned in the particle filter to be cleaned liquid under pressure containing container, an outlet valve and a hose connectable to the outlet valve spray nozzle, which in a space located in front or behind the particle filter in the Exhaust system is insertable. With such a device, the spaces in front of or behind it can be easily reached in the installed state of the particulate filter for cleaning the same.

A particularly advantageous embodiment of the device is characterized in that the spray nozzle is formed as a closed at its free end tube having a plurality of nozzle openings in the peripheral wall of the tube, wherein the nozzle openings are aligned substantially in the longitudinal direction of the tube, so that from the jets emerging from the nozzle openings are substantially parallel and / or lie in one plane.

figure description

• Figur 1: eine schematische vereinfachte Darstellung einer Vorrichtung zur Reinigung von Partikelfiltern in Abgasanlagen,
• Figur 2: eine vereinfachte schematische Darstellung des Teils einer Abgasanlage eines Verbrennungsmotors, der einen Partikelfilter enthält, und
• Figur 3: der in Figur 2 gezeigte Teil einer Abgasanlage während der erfindungsgemäßen Reinigung des Partikelfilters.

The invention will be explained in more detail below with reference to the drawing. Show it:

• FIG. 1 : a schematic simplified representation of a device for cleaning particulate filters in exhaust systems,
• FIG. 2 a simplified schematic representation of the part of an exhaust system of an internal combustion engine, which includes a particulate filter, and
• FIG. 3 : the in FIG. 2 shown part of an exhaust system during the purification of the particulate filter according to the invention.

In the various figures of the drawing corresponding components are provided with the same reference numerals.

As in FIG. 1 is shown, the device for cleaning a in an exhaust system of an in-vehicle particulate filter on a container 10 which receives the injected into the particle filter to be cleaned liquid. The container 10, which is designed as a pressure vessel, either has an integrated pressure accumulator, or can be connected in a manner not shown to a compressed air system to be able to deliver the liquid at high pressure from the container 10. For discharging the cleaning liquid from the pressurized container 10, an outlet valve 11 is provided, the outlet side is connected via a connecting piece 12 with one end of a hose, in particular a pressure hose 13, at the other end of a preferably lance-shaped spray nozzle 14 is attached. The outlet valve 11 can be opened via an operating lever 15 provided in the connection piece 12 in order to be able to dose and selectively discharge cleaning liquid.

The spray nozzle 14 is expediently made of a tube 16, which is pressure-tightly sealed at its free end 17 and adjacent to its free end 17 has a plurality of nozzle openings 18, which are aligned substantially along a parallel to the axis of the tube generatrix of the same, so that the liquid jets 19 emerging from the individual nozzle openings 18 (see FIG. 3 ) are substantially parallel to each other.

Although the lance-shaped spray nozzle is shown as a straight tube in the drawing, with a good cleaning of particulate filters in a variety of installation situations is possible, it is also conceivable to provide for special exhaust systems spray nozzles that are bent or cranked, wherein the nozzle openings 18 supporting free End of the nozzle tube 16, preferably remains straight. But it is also conceivable that the nozzle tube 16 in the region of the outlet nozzles 18 form curved, so that the exiting

Rays divergent or convergent to each other, or continue to be parallel, but no longer in a plane. The curvature can also be such that the individual rays lie on a tapered or diverging cone sheath.

As in FIG. 2 schematically, an exhaust pipe 20 includes an exhaust system of an internal combustion engine in a vehicle, an inlet portion 21 (not shown) connected to an exhaust outlet of an internal combustion engine, an outlet portion 22 leading to the environment, and a cylindrical housing portion 23 therebetween. the opposite to the inlet and outlet sections 21 and 22 has a significantly larger cross-section. In this housing section 23, a catalytic converter for converting carbon monoxide and nitrogen oxides into carbon dioxide or nitrogen, and a particle filter 25 are arranged in conventional exhaust systems usually the inlet, which, as already explained, incompletely burned fuel components, ie soot, from the environment filter out exhaust gas to be dispensed.

In order to control the internal combustion engine, in particular the diesel engine of the motor vehicle, in such a way that the environmental and climate-damaging exhaust gas components are minimized as far as possible, various sensors are mounted on the housing section 23 and passed through corresponding openings in the housing wall. In the FIG. 2 For the sake of simplicity, only two pressure sensors 26, 27 are shown, which are arranged upstream or downstream of the particle filter 25, in order to be able to detect the loading state of the particle filter 25 on the basis of the determined pressure differences.

In order to purify a particulate filter 25 located in the exhaust system by means of the method according to the invention, preferably an opening 30 leading into the interior of the housing 23 in front of the particulate filter 25 to be cleaned is uncovered. In the example shown, the opening provided for the pressure sensor 26 is released by disassembling the pressure sensor 26. However, any other suitable opening which is or should be present in this housing area can also be used for carrying out the method according to the invention. As soon as the opening 30 in the housing 23 is open, the lance-shaped spray nozzle 14 of the housing 23 introduced so that the nozzle openings of the elnlassseitigen end face of the particulate filter opposite. In order to simplify the alignment of the nozzle openings to the particle filter towards, a corresponding mark 31 may be attached to the pipe of the spray nozzle 14, as shown in FIG. 3 is indicated.

If, depending on the design of the exhaust system, the space in front of the particulate filter is not accessible by simply disassembling sensors or the like, a corresponding sensor protruding in the space behind the particulate filter 25 as seen in the flow direction can also be removed, and then the spray nozzle there 14 introduce, as in FIG. 3 is shown.

After insertion of the spray nozzle, the outlet valve 11 of the container 10 is opened by actuating the lever 16, so that the cleaning liquid can be injected from the inlet side into the particle filter at a pressure of 5 to 12 bar, in particular 6 to 8 bar. In this case, the spray nozzle is moved with its front end so that, if possible, the entire inlet-side end face of the particulate filter 20 is sprayed with cleaning liquid in order to achieve that the entire interior of the particulate filter is substantially completely soaked.

In carrying out the method according to the invention, the injection of the cleaning liquid into the particle filter 25 can be carried out so that the total amount of cleaning liquid to be injected, which preferably corresponds to half the volume of the particle filter 25, is injected continuously in succession.

However, it is also conceivable to carry out the injection of the cleaning liquid into the particle filter 25 in two, three or four passes, wherein waiting times are kept between the individual injection processes whose duration in the range between 1 to 10 minutes, preferably between 3 and 7 minutes, in particular 5 minutes. This makes it possible for the cleaning liquid to penetrate more easily deeper into the particle filter 25, which is advantageous in particular in the case of particulate filters 25 that are added very heavily.

Further, if both the space in front and the space behind the particulate filter 25 are accessible, it is possible to inject a part of the cleaning liquid from the inlet part of the particulate filter 25 and another part thereof from the outlet side. If in this case the cleaning liquid is injected with more than two injection processes, the cleaning liquid can be alternately injected first from the outlet side and then from the inlet side to shorten the waiting time. As a result, the complete wetting of the interior of the particulate filter can be further improved.

Once the entire intended for the cleaning process cleaning liquid was injected, either the housing can be closed again by inserting the corresponding sensors, so that the cleaning liquid is forced out of the particle filter during the following operation of the internal combustion engine in the workshop, and it is carried out according to the invention a rinsing process, in which preferably an ashless, non-flammable flushing liquid is injected into the particle filter from the inlet side so as to remove at least part of the cleaning liquid and soot particles located therein from the particle filter before the internal combustion engine is put into operation. In this case, the injection of the rinsing liquid expediently takes place with the same pressure as the injection of the cleaning liquid, but with a reduced amount.

After cleaning the particulate filter, an active regeneration of the particulate filter is expediently carried out in order also to remove soot particles which may still have remained in the particulate filter after cleaning.

The method according to the invention can be carried out in a simple manner in any motor vehicle workshop, without involving elaborate removal and modification work on the exhaust system or exhaust system of a vehicle. Since in this way the life of the exhaust system can be significantly extended, this has considerable time and Kostenvortelle for the vehicle operator.

Claims (11)

1. A method for cleaning particle filters being arranged in exhaust gas systems of combustion engines, in particular diesel engines in vehicles, in which

   - an opening (30) leading into the interior of the housing (23) before or after the particle filter (25) to be cleaned is exposed,

   - a spray nozzle (14) is inserted into the interior of the housing (23) in such a way that the nozzle openings (18) lie opposite an end face of the particle filter through which exhaust gas flows during the operation of the combustion engine; and

   - a noncombustible, ash-free cleaning fluid is sprayed into the particle filter (25) at a pressure of from 5 to 12 bar by means of the spray nozzle (14), across the area of said filter through which the exhaust gas flows during the operation of the combustion engine, in a quantity corresponding approximately to half the volume of the particle filter (25) such that the interior of the particle filter is substantially completely soaked.
2. The method as claimed in claim 1, wherein the cleaning fluid is injected at a pressure of from 6 to 8 bar.
3. The method as claimed in claim 1 or 2, wherein the cleaning fluid is injected successively in two, three or more portions.
4. The method as claimed in claim 3, wherein the time between the individual injection operations is from 1 to 10 minutes, preferably from 3 to 7 minutes, in particular 5 minutes.
5. The method as claimed in one of the preceding claims, wherein the cleaning fluid is injected into the particle filter when the latter is at a temperature of from 10°C to 100°C, preferably of from 40°C to 70°C.
6. The method as claimed in one of the preceding claims, wherein an ash-free, noncombustible flushing fluid is sprayed into the particle filter after the injection of the cleaning fluid.
7. The method as claimed in claim 6, wherein the flushing fluid is injected at the same pressure as the cleaning fluid.
8. The method as claimed in claim 6 or 7, wherein the flushing fluid is injected after a waiting time following the ending of injection of the cleaning fluid which is equal to or longer than the time between the individual injection operations for cleaning fluid.
9. The method as claimed in one of the preceding claims, wherein the cleaning fluid is an aqueous alkaline fluid.
10. Use of an apparatus having:

    - a container (10) containing, under pressure, the fluid to be injected into the particle filter (25) to be cleaned,

    - an outlet valve (11), and

    - a spray nozzle (14), which can be connected to the outlet valve via a hose (13) and can be inserted into a space in the exhaust gas system situated before or after the particle filter (25)

    for carrying out the method according to one of the preceding claims.
11. Use as claimed in claim 10, wherein the spray nozzle (14) is designed as a tube (16) which is closed at its free end (17) and has a plurality of nozzle openings (18) in the circumferential wall of the tube (16), the nozzle openings (18) being aligned substantially in the longitudinal direction of the tube (16), with the result that the jets emerging from the nozzle openings are substantially parallel and/or are in one plane.

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